Tunneling Lifetime Broadening of the Quantum Well Intersubbard Photoconductivity Spectrum.

We have measured, for the first time, the continuous infrared (lambda ~ 10microns) photoconductivity spectrum, for an intersubbard absorption photoexcited tunneling quantum well detector. The line shape is broadened and asymmetrical with respect to the zero bias Lorentzian absorption spectrum. We show that this a result of the uncertainty principle lifetime broadening due to the rapid tunneling escape of the photoexcited electrons.